In Canada, when it comes to figuring out how much pollution the oil sands emit, the government relies on industry to report their own numbers. That's how policies get made and regulations are formed, but it turns out the oil sands companies have been significantly underestimating the level of a certain type of pollution they emit.

Back in 2013, researchers gathered their own data by flying above and around four different oil sands facilities at different altitudes. Dr. Shao-Meng Li, a senior research scientist for Environment and Climate Change Canada and lead author of the study, says he found the oil sands producers were emitting two to four-and-a-half times more volatile organic compounds than they had reported. Those are gaseous organic compounds that can be toxic for human and environmental health.

Dr. Kelly Munkittrick, the director of monitoring for COSIA, an alliance of oil sands producers working together on research and development around environmental performance. He says the industry's aware of this issue of uncertainty in their reported volatile organic compounds levels. "This is really one piece in a complicated puzzle. Industry's got a bunch of other studies looking at other pieces. And at some point it's all got to be brought together to try and turn into - what is the best approach to try and get more consistent monitoring of this kind of information."